1. Field of the Invention
This invention relates to detergent compositions for clothing and more particularly, to clothing detergent compositions comprising a cellulase which has a good dirt-removing action and a good non-degrading property for insoluble celluloses including cotton.
2. Description of the Prior Art
In the field of clothing detergents, it is known that detergent compositions comprising cellulases are effective in removing dirt when used to wash clothing articles containing cellulosic fibers such as cotton and regenerated cellulose fibers (Japanese Pat. Publication No. 59-49279) and are also effective in mitigating roughness by washing of clothes to the touch (Japanese patent application Laid-open Ser. No. 57-23699).
Since an aqueous solution of a detergent for clothing dissolved in water is neutral to alkaline in nature and is usually weakly alkaline, the cellulase used for this purpose is favorably an alkalophilic cellulase. Although applications of such a cellulase to detergents for clothing are not so popular, only several instances are known such as described, for example, in Japanese patent application Laid-open Ser. No. 57-145199.
Cellulase is a generic term for enzymes which act on cellulose and its derivatives and hydrolyze them into glucose, cellobiose, cellooligosaccharide. It has been called in various names depending upon the working mechanism, but the true nature of the cellulase has not been known yet. In this connection, however, the cellulase having the effect of removing dirt (Japanese Pat. Publication No. 59-49279) and the cellulase having the effect of mitigating the roughness to the touch (Japanese patent application Laid-open Ser. No. 57-23699) are considered to have substantially different working mechanisms from each other.
In view of the differences in working mechanism among cellulases, when cellulases act on fibers made of cellulose and cellulose derivatives, various effects may be expected including removal of dirt such as soil, mitigation of roughness to the touch, prevention of fading (decoloration) of colored clothing articles and the like. Instead, there is the fear that cellulose and cellulose derivative fibers may be damaged. Especially, in home washing using a washing machine with a strong mechanical force, a serious problem of mechanical damages, in fact arise. If the cellulose fibers are damaged with cellulases, the above problem will become more serious.
When attention is given to effective utilization of cellulose as a carbon resource, i.e. when solid cellulose is saccharified and the resultant product is used as a carbon source for alcohol fermentation, a cellulase having good capability of saccharification of solid cellulose is necessary. This type of cellulase exhibits the capability of saccharification against cotton. Accordingly, when the cellulase is applied to a detergent for clothing, there is the danger that the cotton suffers damages or degradation.
Only one alkali-resistant cellulase which is currently available for detergent purposes is Celluzyme 2400T, commercially sold from Novo Industry (Japanese patent application Laid-open Ser. No. 57-23699). This cellulase has fairly good dirt-removing effect but is inferior from the viewpoint of damage-suppressing property of cotton.
Accordingly, there is a demand for the development of a cellulase which does not damage and degrade clothing articles of cellulose fibers such as cotton, rayon, hemp and the like and mixed fibers thereof when used in neutral to alkaline, especially, weakly alkaline, clothing detergents and which has a satisfactory dirt-removing effect, and also of clothing detergent compositions comprising such a cellulase.